Big umbrellas: They’re the latest head-scratcher at Lawrence City Hall. No, really, if you’re not careful, you’ll scratch your head on one of them strolling down a Massachusetts Street sidewalk.

City commissioners at their Tuesday evening meeting are set to create stricter regulations on when restaurants can use umbrellas as part of their sidewalk dining areas.

“It is really just a pedestrian safety issue that we’re trying to respond to,” said Planning Director Scott McCullough, whose office is proposing the regulations after city commissioners directed staff members to look at the issue.

Commissioners heard a few concerns that the umbrellas hung so low that even moderately tall people may bang their heads on the umbrellas, if they aren’t paying particular attention while walking.

City officials are now proposing an addition to the city’s sidewalk dining code that requires the lowest point of any umbrella to be at least 80 inches above the sidewalk.

Staff members said commissioners also could require that none of the umbrellas be allowed to overhang the area outside the fenced-in sidewalk seating area. Or, commissioners could ban the large umbrellas all together. Staff members, though, aren’t recommending either change.

“I think they are a very reasonable sidewalk dining amenity to have, and can fit in well with downtown,” McCullough said. “We just want them to be safe for pedestrians.”

Commissioners at their weekly meeting also will consider tweaking a few other downtown regulations. They include:

• Limiting the size and number of outdoor sandwich sign boards a business may have. The new regulations would prohibit any outdoor sandwich boards from being larger than 32 inches wide and 48 inches tall. All sign boards also would have to be placed no farther than 12 inches from the building, and a business would be limited to one outdoor sign per entrance.

The sandwich boards currently are illegal in the city’s sign code, but staff members are suggesting new regulations because businesses have shown a strong desire to use the signs. On a recent inspection, city officials found 35 of the signs along Massachusetts Street.

• Reaffirming that banner signs, such as those that hang from sidewalk dining rails advertising drink specials, generally are prohibited. Use of balloons or other similar types of devices to draw attention to a business also aren’t permitted under the city’s sign code. If commissioners approve the new regulations, McCullough said businesses should expect some changes in how the sign code is enforced.

“We would want to get our inspection program a little beefier for downtown, if this is adopted,” McCullough said.

• A new regulation requiring that music played in outdoor dining areas, such as ambiance music through a speaker, not be audible more than 20 feet outside the sidewalk dining area.

Tom Wilson, general manager and owner of Teller’s, at 746 Massachusetts Street, said the changes sounded workable as long as commissioners realized such items as umbrellas and mood music were important in the highly competitive restaurant business.

“I can see their point on some of the music,” Wilson said. “There are some restaurants that blast their music so loud that you can’t even carry on a conversation. But it is important to allow some level of music because we’re trying to encourage a fun atmosphere.”

As for umbrellas, Wilson said the change may be costly for some businesses. He said the large umbrellas at Teller’s cost about $500 apiece, and he had to hire a Lawrence metal worker to build special poles in order to raise the umbrellas up to an acceptable height.

McCullough said if the new regulations are approved, his office will inspect sidewalk dining locations for compliance one to two times per year.

Commissioners meet at 6:35 p.m. on Tuesday at City Hall.